1. Field of the Invention
This invention relates to distance measuring systems, and more particularly to distance measuring systems for determining the distance between a golfer and a plurality of features on a golf course, including greens and associated pins, water traps, sand traps, and the like.
2. Description of Related Art
During the course of playing a game of golf, the golfer must often determine the distance between the golf ball and the pin of the next green. Knowing the distance that the ball must travel is one of the most important factors the golfer must consider for selection of the proper golf club. In addition, there may be topographical hazards on the course, such as sand or water traps, the current ball distances to which are desired by the golfer.
To estimate these aforementioned distances, the golfer can rely on experience and course knowledge. The results of estimating these distances can vary a great deal, even by the same golfer on different portions of the same course.
In addition, there are known distance measuring systems for golf course application that may produce varying degrees of success.
U.S. Pat. No. 4,136,394 to Jones et al. discloses a golf yardage indicator system that utilizes a remote unit to be carried by the golfer, and a base unit located at or near the pin on the green. The remote unit can transmit a radio pulse to the base unit, which responds with an acoustic signal. The remote unit determines the distance to the base unit by the time interval between transmission of the radio pulse and reception of the acoustic signal based upon the speed of sound through air.
The main problem with the device of the '394 patent is that, in addition to the remote unit, each pin on each green must have a base unit installed, and maintained. With only one golfer, there would be 19 units, consisting of one remote unit for the golfer and 18 base units for the pins. Add golfers, and the number of remote units required increases accordingly. If the distance to other golf course features such as traps were also desired, an additional base unit would be required at each feature. Thus, requiring an increasing number of base and portable units.
If, instead of multiple base units, one base unit could be carried by the golfer and placed upon each pin or feature, the delay in the game required by the golfer walking to each pin, depositing the base unit, and walking back to the golf ball would not be acceptable.
U.S. Pat. No. 4,703,444 to Storms, Jr. et al. discloses a device for determining distances to features on a golf course that utilizes a portable interrogation unit and three base station transmitters that are placed in predetermined positions around the golf course. The base stations transmit ranging signals and are placed such that a substantial portion of the course is within a triangle defined at its vertices by the three stations. The portable unit stores the known locations of the base transmitters and known locations of features on the course. The ranging signals are received and processed by the portable unit to determine the position of the portable unit in relation to the base units, and the distances from the portable unit to the known locations stored in memory. To determine the position of various features on the course, a survey unit is provided which is utilized to determine each feature's position relative to the base units. Each position is stored in the survey unit and then transferred to the portable interrogation unit's memory.
The device of the '444 patent requires a portable unit for each golfer, and three base station units, for a minimum of four units for one golfer. Each feature of the golf course, from which a distance or range to may be desired, must be presurveyed and entered into memory. Accurate position and ranging information is limited to the area within the triangle defined by the position of each base unit.
There is a need for a distance measuring system for golf course use that addresses some of the limitations discussed herein above.